/*
2020??5??16??12:26:55
1(3):???????????????????????????

2020??5??16??12:42:10
?????????????????????
????????O(n);
*/

void trans(int a[], int n) //a[]???????????n?????A??
{
	int temp;
	for (int i = 0, j = n - 1; i < j; i++, j--)
	{
		temp = a[i];
		a[i] = a[j];
		a[j] = temp;
	}
}
